Sidelink LBT Status Reporting on Dedicated Uplink Resources
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Solution Overview
Problem
Existing wireless communication systems face challenges in efficiently managing listen-before-talk (LBT) procedures for sidelink channels, particularly in unlicensed bands, leading to increased latency and resource inefficiencies in reporting LBT statuses to base stations.
Innovation Solution
A method and apparatus for UEs to report LBT statuses on dedicated uplink resources separate from sidelink transmission acknowledgement messages, allowing for reduced latency and more accurate reporting of LBT statuses to base stations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a UE performs LBT and detects the channel is busy, then the UE must drop the scheduled PUSCH transmission, but this causes uplink data transmission failure and requires retransmission
Solution Approach 1:
The gNB performs downlink pre-emption indication (PDI) in advance to notify the UE about uplink resource pre-emption before the UE transmits. This preliminary notification allows the UE to prepare for potential resource dropping and switch to alternative transmission methods (like PUCCH or PUSCH on another carrier) without waiting for the actual collision to occur, thereby reducing transmission delay while maintaining reliability.
Solution Approach 2:
The gNB sends downlink pre-emption indication (PDI) as feedback to the UE regarding the status of uplink resources. This feedback mechanism allows the UE to understand whether its scheduled transmission will be preempted and take appropriate actions. The feedback loop between gNB and UE enables dynamic adaptation of transmission strategies, improving both reliability and timing efficiency.
2Adaptability or versatility
If the network configures multiple uplink carriers for a UE, then the UE has more options for alternative transmission, but this increases device complexity and configuration overhead
Solution Approach 1:
The UE autonomously determines which alternative uplink carrier to use for transmission based on the pre-emption indication received and its own stored configuration information. Instead of requiring complex real-time network control for each carrier selection, the UE serves itself by making intelligent decisions based on pre-configured parameters and current channel conditions, thereby reducing overall system complexity while maintaining flexibility.
Solution Approach 2:
The system dynamically selects uplink carriers based on real-time pre-emption conditions rather than using fixed static configurations. The UE can switch between different uplink carriers (PUCCH on different carriers, or PUSCH on different carriers) depending on which resources are available at the moment of transmission, creating a dynamic adaptation mechanism that balances flexibility with manageable complexity.
3Productivity
If the UE switches to alternative uplink resources when primary resources are preempted, then data transmission can continue, but this increases signaling overhead and resource management complexity
Solution Approach 1:
The gNB pre-configures alternative uplink resources and transmission parameters before the UE needs them. When pre-emption occurs, the UE simply activates pre-prepared alternative resources rather than performing complex real-time resource allocation. This preliminary preparation significantly reduces the computational burden and signaling overhead during actual transmission switching events.
Solution Approach 2:
The system creates copies of essential transmission configurations for multiple uplink carriers in advance. The UE stores duplicate configuration information (such as PUCCH resources, PUSCH parameters) for different carriers, allowing it to quickly switch to a pre-configured copy when the primary resource is preempted. This copying approach eliminates the need for complex real-time configuration generation and reduces signaling overhead.
Data Source
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AI summary
Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive, from a base station, a resource grant for at least one sidelink channel, wherein the resource grant indicates a first uplink resource for transmitting sidelink transmission acknowledgement messages and a second uplink resource for transmitting listen-before-talk statuses. The UE may transmit, to the base station and on the second uplink resource, an indication of at least one status associated with a listen-before-talk procedure used on the at least one sidelink channel. Numerous other aspects are provided.